Background technology
Base station (BTS in traditional code division multiple access (CDMA) system, be also referred to as " Node B ") and mobile radio station (MS is also referred to as " subscriber equipment ") between Traffic Channel comprise a forward channel (being also referred to as " downlink channel ") and backward channel (being also referred to as " uplink channel ").At this moment, base station and be positioned at a plurality of forward channels between a plurality of mobile radio stations of overlay area (sub-district) of a base station to be based on timing information synchronized with each other.Therefore, when restituted signal, the interference between the forward channel can reduce considerably by using orthogonal orthogonal code.
But owing to do not use timing information in backward channel, backward channel can not be synchronous.Along with the increase of backward channel quantity, the interference between backward channel has increased.Therefore, the capacity of backward channel is restricted.
For increasing the capacity of backward channel, need make a plurality of backward channels synchronous according to identical timing information.Backward channel is by synchronously, and each synchronous backward channel is discerned by orthogonal code, and then the interference between backward channel can minimize.This method is called as " up-ward link synchronous transmission program (USTS) ".The USTS technology has been discussed in the conference group of asynchronous international mobile telecommunication 2000 (IMT-2000) system standardization.
In using the system of USTS, the backward channel the sub-district in is by synchronously, and according to discerning each backward channel by orthogonal code synchronously between MS and BTS, thereby cause serious problems, use the soft handover method of diversity to be difficult to execution.Therefore, use the changing method in the system of USTS, need it that mobility of MS is provided and do not provide.
Traditional changing method will describe in detail with reference to Fig. 1 and 2.
Fig. 1 is the flow chart that expresses support for method for hard switching traditional in the radio telecommunications system of USTS.
At first, radio network controller (radio network controller, RNC) 30 in step 101 and 102 (source base transceiver station BTS) 21 send to measure control messages to mobile radio station (mobile station, MS) 10 by the source base transceiver station.MS 10 measure new target BTS pilot signal power level and report that by sending measurement report information measurement result is to RNC 30 by source BTS 21 in step 104 and 105.
RNC 30 determines whether to carry out in step 106 and switches, and divides the scrambling code and the channel code that are used in USTS, and is established to target BTS 22 at step 107 request radio link.Target BTS 22 is set up a forward link channel in step 108, and sends radio link setup response message to RNC 30 in step 109 subsequently.Transport vehicle new between RNC 30 and the target BTS 22 is established in step 110.
RNC 30 step 111 and 112 by source BTS 21 send scrambling code, channel code with USTS, the physical channel that is used for the initial synchronisation information of target BTS 22 reconfigures information to MS 10, request MS 10 carries out reconfiguring of physical channels.MS 10 sets up new radio channel sign indicating number in step 113 based on the USTS sign indicating number, and sends physical channels in step 114 and 115 subsequently and reconfigure and finish message to RNC 30.If physical channel reconfigure failure, source BTS 21 sends radio link in step 116 and sets up failed message to RNC 30.
If reconfiguring of physical channel finished, RNC 30 sends radio link in step 117 and discharges request message to source BTS 21, and discharges with the radio link of MS 10 and send radio link in step 118 with opisthogenesis BTS 21 and discharge response message to RNC 30.
In above-mentioned method for hard switching, RNC 30 should store the average roundtrip delay value of the MS that will be switched and know chip offset accurately by the chip level between the BTS.But, owing to be difficult to obtain when switching regularly synchronously accurately, regularly synchronously should be by regularly following the tracks of compensation.Therefore, have a problem, mode switch is to very difficult execution of USTS pattern a period of time after switching.
Fig. 2 is the flow chart that is illustrated in a traditional soft handover method in traditional asynchronous wireless telecommunication system.
At first, radio network controller (RNC) 30 sends by source base transceiver station (BTS) 21 in step 201 and 202 and measures control messages, and mobile radio station (MS) sends measurement report information at the power level of the pilot signal of step 203 measurement target BTS 22 and in step 204 and 205 by source BTS 21 subsequently, gives RNC 30 with measurement report.
RNC determines whether switching is carried out, and in other words, need to determine whether other link in step 206.Switch if desired, RNC 30 sets up radio link at step 207 request target BTS 22, and in step 208 and 209, if radio link route target BTS 22 is set up and received radio link setup response message from target BTS 22, then set up the new transport vehicle of target BTS 22.If RNC 30 sends down link (downlink in step 210, DL) synchronizing information is given target BTS, the time of advent, (time of arrival ToA) sent up link (uplink, UL) synchronizing information to target BTS 22 afterwards in measuring in step 211 and 212.
RNC 30 sends active set update request information by source BTS 21 to MS 10 in step 213 and 214.MS upgrades active set, and upgrades finish information by target BTS 22 to RNC 30 transmission active sets in step 215 and 216 subsequently.
RNC 30 discharges radio link at step 217 request source BTS 21, and subsequently after the radio link of release and MS, in step 218, source BTS sends radio link to RNC 30 and discharges response message, thus the transport vehicle between step 219 release RNC 30 and source BTS.
In above-mentioned soft handover method, also combination is from the signal of at least two BTS according to diversity reception for MS, if one of signal dies down, then subsequently, the radio source that sends the BTS of weak signal is released.
Move to the situation of the sub-district of not supporting USTS in order to use soft handover method from the sub-district of supporting USTS to mobile radio station, should discern MS.In other words, in common IMT-2000 system, mobile radio station is discerned by scrambling code, and still, in the mobile radio station of supporting USTS, scrambling code is used to discern sub-district, i.e. BTS.Therefore, if a plurality of mobile radio station attempts to carry out simultaneously soft handover, as the signal from a mobile radio station, signal just can not be decoded like this from all signals of a plurality of mobile radio stations for target BTS identification.If mobile radio station is in the moving between cells of supporting USTS, because different scrambling codes is used for each BTS, mobile radio station should have two or more transmitters.
Embodiment
Up-ward link synchronous transmission program (USTS) technology is described at first, in more detail.
In the system that supports USTS, by being controlled at the transmission time of Frame in the backward channel, promptly, from the transmission time of the Frame of MS in its sub-district, BTS makes reverse signal use orthogonal code to arrive BTS simultaneously, and therefore the characteristic of orthogonal code can be maximized, thereby increases the transmission capacity of sub-district considerably.
In other words, the USTS efficient forward channel no better than that increased backward channel.For USTS, scrambling code and orthogonal channel sign indicating number are used to discern the channel of sub-district and mobile radio station.BTS has the reference time of its sub-district, and initial insert BTS before MS do not influence reference time of BTS.
If MS attempts to insert BTS by Random Access Channel, BTS is by obtaining to insert the roundtrip delay time of calculating MS the time of advent of signal.If the time of advent from the reverse signal of MS is faster than the reference time, the message transmission time delay among the MS time difference between the time of advent and reference time.On the contrary, shifted to an earlier date should the time difference message transmission time among the MS.Therefore, according to reverse signal at synchronous each MS time of advent of BTS.The initial synchronisation information that reverse signal needs synchronously is inserted into the forward direction signaling message, and it is in response to initial access, and is transferred to MS subsequently.
When attempting inserting BTS at random and asking the dedicated channel sign indicating number, carries out MS the process of initial synchronisation.If MS obtains initial synchronisation, then be applied to the transmission of dedicated channel synchronously.After this in the transmission of dedicated channel, keep regularly synchronously according to dedicated signaling.
Regularly make orthogonal code be used to the signal that sends from MS synchronously, each MS uses identical scrambling code.Orthogonal code has than data transmission rate chip-rate faster, and therefore, the transmission data bandwidth that multiply by orthogonal code is increased to 1/ chip-rate.Orthogonal code is called as " extended code ".In forward channel, orthogonal code is also referred to as " channel code ".Because orthogonal code and same code have high correlation, orthogonal code is correctly decoded.But orthogonal code and other sign indicating number have zero (0) correlation.Each channel of a plurality of backward channels from a plurality of mobile radio stations to the base station multiply by different orthogonal codes with identification channel and multiply by identical scrambling code subsequently with synchronous a plurality of backward channels.
The USTS technology is used for identical scrambling code a plurality of channels and orthogonal code is used for each channel of MS in a sub-district, can improve systematic function, and wherein MS moves hardly, in other words, does not have switching.
When carrying out switching in the system that is supporting USTS, there are some problems, the timing that identical channel code should be distributed between backward channel and different scrambling code in a new sub-district should be synchronous.Diversity can not be used to support the radio telecommunication system of USTS, and wherein signal and this signal that receives from a MS at a plurality of BTS makes up in network, thereby reduced systematic function between transfer period.
In order to carry out the soft handover of MS, the frequency that is used for the channel of transmission data from BTS to MS should be identical, and should transmit data simultaneously to two BTS for MS.But in the backward channel of the MS that supports USTS, because the sub-district is based on scrambling code identification, MS can not transmit data simultaneously and give two BTS.In addition, discerned by orthogonal code owing to have each channel of the MS of identical scrambling code, identical channel code is difficult to re-use when carrying out switching.Therefore, support the MS of USTS to be switched based on method for hard switching and the sub-district of Ying Zaixin in obtain initial synchronisation.
Among the present invention,, before switching, carry out the mode switch of USTS pattern and non-USTS pattern according to signal measurement result by the MS report in order to address the above problem.
As MS during in the operation of non-USTS pattern, scrambling code and channel code resemble each channel that is respectively applied for each MS of identification and uses MS in common asynchronous IMT-2000 system.Therefore, the MS of non-USTS pattern can switch based on the changing method in all common IMT-2000 systems.The USTS pattern has the advantage under the environment of not carrying out switching.Therefore, by using two kinds of patterns, can under the situation that does not reduce performance, carry out switching.
Below, describe the preferred embodiments of the present invention with reference to the accompanying drawings in detail.
Fig. 3 represents according to the present invention the flow chart of initial synchronisation catching method in the asynchronous wireless telecommunication system of supporting USTS.
A mobile radio station (MS) passes through Random Access Channel (RACH) in step 301, ask base transceiver station (BTS) to set up or set up again radio resource control (radio resource control, connection RRC) by sending the USTS identifier of representing USTS whether to support to BTS.BTS 20 measures the roundtrip delay time be used for Initial R ACH transmission data in step 302, and sends USTS identifier and roundtrip delay time to radio network controller (RNC) at the Frame of step 303 by Frame Protocol RACH (FP-RACH).
RNC 30 determines whether MS supports USTS.If MS supports USTS, then RNC 30 is used for scrambling code and the channel code of USTS in step 304 according to the channel allocation mode assignments, and calculates the initial synchronisation timing information according to reference time of sub-district and reference time and the difference of roundtrip delay between the time.RNC 30 sends the scrambling code of initial synchronisation timing information, USTS and channel code to BTS at the Frame of step 305 by Frame Protocol-forward direction accidental channel (FP-FACH), and subsequently in step 306, BTS20 asks MS10 foundation or sets up RRC again to be connected to MS 10 with channel code by the scrambling code that sends initial synchronisation timing information, USTS.
MS 10 sets up physical channel in step 307 according to scrambling code and the channel code of USTS, and adjusts the transmission time according to the initial synchronisation timing information.As dedicated channel (the dedicated channel that distributes MS 10 in step 308, DCH) time, MS 10 sends the RRC connection setup complete message to BTS in step 309 by DCH, and BTS 20 sends information corresponding to the RRC connection setup complete message to RNC at the Frame of step 310 by Frame Protocol-dedicated channel (FP-DCH) subsequently.
If set up dedicated channel between MS and BTS, data are transmitted by dedicated channel, and the reference time cause owing to moving of MS and the difference between the transmission time are according to the control information adjustment that sends by dedicated channel.
Fig. 4 A to 4D represents according to the present invention the flow chart of soft handover method in the asynchronous wireless telecommunication system of supporting USTS.
With reference to Fig. 4 A to 4D, soft handover method according to the present invention comprises mode switch process, handoff procedure and the mode switch process from non-USTS pattern to the USTS pattern from the USTS pattern to non-USTS pattern.
Among the present invention, before the switching of mobile radio station (MS) 10, according to the mode switch of signal measurement result execution from the USTS pattern to non-USTS pattern.Source radio network controller (RNC) 31 sends in step 401 has the measurement control messages of USTS mode switch condition to MS 10.
In step 402 and 403, MS 10 measures the power level of the pilot signal of current service cell and adjacent cell, and has the measurement report message report measurement result of the information that is used for mode switch and switching to source RNC 31 by transmission.
Source RNC 31 determines in step 404 whether they should carry out switching and the mode switch from the USTS pattern to non-USTS pattern.If the ratio of current service cell pilot signal power intensity and adjacent cell pilot signal power intensity less than one than low threshold, as-5dB, then carry out the mode switch of non-USTS.Source RNC 31 carries out reconfiguring of radio link at step 405 request source BTS 21.Source RNC 31 reconfigures preparation message at the radio link that step 406 receives from source BTS 21, carries out reconfiguring of radio link and carries out reconfiguring of physical channel at step 408 request MS 10 at step 407 order source BTS 21 subsequently.
For the mode switch from the USTS pattern to non-USTS pattern, scrambling code and channel code are assigned to the physical layer of source BTS 21 and MS 10, and after mode switch was finished, MS 10 finished in the foundation of step 409 notification source RNC 31 physical channels.From this moment,, the timing of roundtrip delay carries out because following the tracks of by the receiver of BTS.
For switching, the request radio link is established to Target RNC 32 and target BTS 22.Target BTS is distributed physical channel and is finished the foundation of transport vehicle.
When setting up radio link between source RNC 31 and Target RNC 32, source RNC 31 sends in step 410 has the radio link additional request message of USTS identifier to Target RNC 32.
Target RNC 32 distributes physical channel to set up radio link with sign indicating number and at step 412 request target BTS 22 in step 411 decision.Target BTS 22 is set up physical channel in step 413, subsequently, sends radio link setup response message to Target RNC 32 and begin received signal.
Target RNC 32 sends radio link extraneous response message to source RNC 31 in step 415, synchronous to respond radio synchronization acquistion order in step 416 and 417 foundation from target BTS 22 with the transport vehicle and the execution of target BTS 22, begin transmission/reception subsequently.Those skilled in the art understands that the transmission of radio synchronization acquistion command messages is a supporting process.Target RNC 32 is also set up with transport vehicle and the execution of source BTS 22 synchronous in step 418.
When the foundation of radio channel and transport vehicle was finished, data-signal sent simultaneously by two BTS, and MS 10 combinations are from the data-signal and the decoding data signal of two BTS receptions.
When carry out switching and upgrade active set, the wire/wireless transport vehicle of active RNC 31 and source BTS 21 be released, and Target RNC 32 and target BTS 22 are served MS.
Source RNC 31 upgrades active set at step 419 request MS 10, and MS upgrades active set and sends the active set renewal subsequently in step 420 and finishes information to Target RNC 32.
When source RNC 31 when step 421 request is discharged into the radio link of source BTS 21, source BTS 21 discharges radio link in step 422, sends radio link and discharges response message and also stop transmission/reception.Subsequently, be released in transport vehicle among MS, source RNC 31 and the source BTS 21 in step 423.
After switching, if the ratio of current service cell pilot signal power intensity and a neighbor cell pilot signal power intensity is greater than than high threshold, as 5dB, then MS 10 sends in step 424 and has the measurement report message of mode switch information to Target RNC 32.
The measurement report message that Target RNC 32 receives from MS 10, distribute with current carrier in scrambling code and the channel code of identical USTS, measure bid indicator to target BTS 22 in step 425 by sending chip offset, the reconfiguring of request radio link to obtain the initial synchronisation of assigned code and dedicated channel.Here, for the chip offset between measurement target RNC 32 and the target BTS 22, can additionally use and measure control messages and measure response message.
Target BTS 22 is given Target RNC 32 in step 426 measure and transmit chip offset, and prepares reconfiguring of radio link in step 427.Target RNC 32 is in the time started of step 428 notification target BTS 22 these USTS patterns and reconfiguring of command execution radio link, and target BTS 22 is carried out reconfiguring of radio link subsequently.
Target RNC 32 sends to have to MS in step 429 and need be used for mode switch and reconfigure solicited message to the scrambling code of USTS pattern and the physical channel of channel code and initial synchronisation timing information, thereby command execution USTS operates.MS 10 carries out reconfiguring of physical channel in step 430 according to the parameter that receives, and from non-USTS mode switch to the USTS pattern and subsequently reconfiguring of notification target BTS 32 these physical channels finished.
Those of ordinary skills can know that this embodiment has multiple change and correction.
Situation is the switching from the BTS that supports USTS to the BTS that does not support USTS, wherein only carries out mode switch process and handoff procedure from USTS to non-USTS.In other words, do not carry out mode switch process from non-USTS to USTS.
Another situation is never to support the switching of the BTS of USTS to the BTS that supports USTS, wherein only carries out handoff procedure and the mode switch process from non-USTS to USTS.In other words, do not carry out mode switch process from USTS to non-USTS.
Fig. 5 A to 5D is the flow chart of expression according to the present invention's method for hard switching in the asynchronous wireless telecommunication system of supporting USTS.The soft handover method that method for hard switching among this embodiment is described similar in appearance to reference accompanying drawing 4A to 4D is except only sending data by a radio link.
With reference to Fig. 5 A to 5D, method for hard switching according to the present invention comprises mode switch process, handoff procedure and the mode switch process from non-USTS pattern to the USTS pattern from the USTS pattern to non-USTS pattern.
Among this embodiment, before the switching of mobile radio station (MS) 10, according to the mode switch of signal measurement result execution from the USTS pattern to non-USTS pattern.Radio network controller (RNC) 31 in source sends in step 501 has the measurement control messages of USTS mode switch condition to MS 10.
MS 10 measures the pilot signal power intensity of current service cell and adjacent cell in step 502 and 503, and has this measurement result of measurement report message report of mode switch and handover information to source RNC 31 by transmission.
Source RNC 31 determines whether to carry out switching and the mode switch from the USTS pattern to non-USTS pattern in step 504.If the ratio of current service cell pilot signal power intensity and neighbor cell pilot signal power intensity less than one than low threshold, as-5dB, then carry out the mode switch of non-USTS.Source RNC 31 carries out reconfiguring of radio link at step 505 request source BTS 21.Source RNC 31 receives radio link in step 506 from source BTS 21 and reconfigures preparation message, reconfigures and reconfiguring at step 508 request MS 10 execution physical channels at step 507 order source BTS 21 execution radio links subsequently.
For the mode switch from the USTS pattern to non-USTS pattern, scrambling code and channel code are assigned to the physical layer of source BTS 21 and MS 10, and after mode switch was finished, MS 10 finished in the foundation of step 509 notification source RNC 31 these physical channels.From this moment, carry out because the timing of roundtrip delay is followed the tracks of by the receiver of BTS.
For switching, request is established to the radio link of Target RNC 32 and target BTS 22.Target BTS is distributed physical channel and is finished the foundation of transport vehicle.
When the radio link set up between source RNC 31 and the Target RNC 32, source RNC 31 sends the radio link with USTS identifier in step 510 and sets up request message to Target RNC 32.
Target RNC 32 distributes physical channel and sets up radio link at step 512 request target BTS22 in step 511 decision.Target BTS 22 is set up physical channel in step 513, sends radio link setup response message subsequently to Target RNC 32 and begin received signal.
Target RNC 32 sends radio link setup response message to source RNC 31 in step 515, sets up with the transport vehicle of target BTS 22 in step 516 and also carries out synchronously, begins transmission/reception subsequently.Target RNC 32 is also set up with transport vehicle and the execution of source BTS 22 synchronous in step 517.
Target RNC 32 sends the radio link with USTS coded message and initial synchronisation timing information in step 518 and reconfigures solicited message to MS 10.
If source BTS 21 is invalid at step 519 notification source RNC 31 these radio links, source RNC 31 discharges radio links at step 520 request source BTS 21, and source BTS 21 sends radio link in step 522 and discharges response message to source RNC 31 and stop transmission/reception.Then, the transport vehicle between source RNC 31 and the source BTS 21 is released in step 523.
MS 10 sends radio link in step 524 and reconfigures the information of finishing to Target RNC 32.
After switching, if the ratio of current service cell pilot signal power intensity and a neighbor cell pilot signal power intensity greater than one than high threshold, then MS 10 sends in step 525 and has the measurement report message of mode switch information to Target RNC 32.
The measurement report message that Target RNC 32 receives from MS 10, distribute scrambling code and channel code with USTS identical in current carrier, measure reconfiguring the initial synchronisation with acquisition assigned code and dedicated channel of request by sending chip offset to target BTS 22 request radio links in step 526.Here, for the chip offset between measurement target RNC 32 and the target BTS 22, can additionally use and measure control messages and measure response message.
Target BTS 22 is given Target RNC 32 in step 527 measure and transmit chip offset, and prepares reconfiguring of radio link in step 528.Target RNC 32 is in the time started of step 530 notification target BTS 22 these USTS patterns and reconfiguring of command execution radio link, and target BTS 22 is carried out reconfiguring of radio link subsequently.
Target RNC 32 sends to have to MS 10 in step 529 and need be used for reconfiguring solicited message to the scrambling code of the mode switch of USTS and the physical channel of channel code and initial synchronisation timing information, thus command execution USTS operation.MS 10 carries out reconfiguring of physical channel in step 531 according to the parameter that receives, and from non-USTS mode switch to the USTS pattern and subsequently reconfiguring of notification target BTS 32 these physical channels finished.
Those of ordinary skills can know that this embodiment exists multiple change and correction.
Situation is the switching from the BTS that supports USTS to the BTS that does not support USTS, wherein only carries out mode switch process and handoff procedure from USTS to non-USTS.In other words, do not carry out mode switch process from non-USTS to USTS.
Another situation is never to support the switching of the BTS of USTS to the BTS that supports USTS, wherein only carries out handoff procedure and the mode switch process from non-USTS to USTS.In other words, do not carry out mode switch process from USTS to non-USTS.
Hereinafter, the mode switch process from non-USTS to the USTS pattern 6 to 10 is described in detail with reference to the accompanying drawings.
Usually, when switching be done and MS and USTS pattern in previous sub-district between link when being released, have the radio link between MS and the new sub-district of in non-USTS pattern, communicating by letter.
Therefore, the mode switch from non-USTS pattern to the MS of USTS pattern is necessary.For mode switch, the timing between BTS and the MS is adaptive should be carried out smoothly.
Adaptive for level and smooth timing, (dedicated physical control channel, transmission time started DPCCH), the roundtrip delay of DPCCH and reference time T_ref calculate the time difference between reference time and transmission time started to RNC according to the Dedicated Physical Control Channel that sends from BTS to MS.This time difference is sent to BTS and MS, and is used for subsequently adjusting the transmission time started of DPCCH and being used for adjusting DPCH (dedicated physical channel, transmission time started DPCH) at MS at BTS.
Be used for according to the reference time needs USTS transmission time two kinds of situations are arranged synchronously.A kind of situation is that the transmission time is by in advance.Another kind of situation is to be delayed in the transmission time.
For adapting to initial synchronisation regularly, the transmission of the frame of DPCH should be adjusted by time difference T_differ.If delay-time difference T_differ is answered in the transmission of the frame of DPCH, then transmission has been interrupted time difference T_differ.On the contrary, if it's pre-set time should to T_differ the transmission of the frame of DPCH, then the DPCH frame overlaps the DPCH frame that sends before the USTS pattern, thereby loses overlapping Frame.
Therefore, the method that needs a kind of Frame that prevents loss.The compact model that is used to switch in wideband CDMA (W-CDMA) system can address this problem.
When calculating is used for time difference from non-USTS pattern to the mode switch of USTS pattern, BTS increases data transmission rate at once, data transmission period reduces, and another operation as can carry out one period free time synchronously regularly thereupon, and this is called " compact model ".
Shifting to an earlier date and postponing of the i.e. timing of at first, regularly synchronous situation described with reference to Fig. 6 and 7.
Fig. 6 is expressed as the synchronization timing that adapts to USTS and the timing diagram that makes the situation that the transmission time started shifts to an earlier date.Fig. 7 is expressed as the synchronization timing that adapts to USTS and the timing diagram that makes the situation that the transmission time started postpones.
With reference to figure 6 and 7, when system works during in non-USTS pattern, high digit time slot is represented the timing of mobile communication system; And when system works during in the USTS pattern with low digit time slot representative.
For the mode switch from non-USTS pattern to the USTS pattern, radio network controller (RNC) calculates reference time T_ref and the time difference of data frame transfer between the time started according to the transmission time started of reference time T_ref (being reference synchronization), down link (DL) Dedicated Physical Control Channel (DPCCH) frame and the arrival time started of up (UL) link DPCH (DPCH) frame.In this case, can select two reference times according to the arrival time started of up link DPCH.In other words, first reference time and second reference time are arranged, the arrival time started that they are based on up link DPCH Frame before the reference time and soon afterwards.RNC can obtain each and have first and second time difference T_differ1 and the T_differ2 that are worth between 1 and 256 chips.
If the time after the arrival time started of up link DPCH Frame soon is selected as the reference time, calculate initial time difference T_differ_init and make comparisons with the value of deducting from the initial time difference T_differ_init of 256 chips, less subsequently value is selected as time difference T_differ.If initial time difference T_differ_init is set to the time difference, then the transmission of Frame should postpone to be used for the time difference of synchronous adaptation.If the value of deducting is set to the time difference, then transmission should in advance should the time difference.
On the other hand, if the time before the arrival time started of up link DPCH Frame soon is selected as the reference time, calculate initial time difference T_differ_init and make comparisons, and less subsequently value is selected as time difference T_differ with the value of deducting from the initial time difference T_differ_init of 256 chips.If initial time difference T_differ_init is set to the time difference, then the transmission of Frame should be used for the time difference of synchronous adaptation in advance.If the value of deducting is set to the time difference, then transmission should postpone this time difference.
For adapting to initial synchronisation regularly, the transmission of DPCH frame should be adjusted by time difference T_differ.If the transmission delay of DPCH frame time difference T_differ, then transmission being interrupted time difference T_differ.On the contrary, if the transmission of DPCH frame should be in advance should time difference T_differ, then the DPCH frame overlaps the DPCH frame of transmission before the USTS pattern, thereby loses overlapping Frame.
Therefore, the method that needs a kind of Frame that prevents loss.As above-mentioned, the compact model that is used to switch in wideband CDMA (W-CDMA) system can address this problem.
The compact model that is used in the W-CDMA system can reduce the substantial data transmission time and reaches 5ms by increasing the 10ms Frame data transfer rate that sends at once, and therefore, another operation can be carried out by mobile radio station in remaining free time.The control of free time is carried out in the unoccupied place during according to one of time slot of information of controlling the transmission of (RRC) message by the Node B application protocol (NBAP) and the radio resource of Iub interface.Compact model is applied to two continuous Frames, and transmission can be interrupted and reaches 10ms.
For of the timing of applied compression pattern, only need the last time slot #15 or the first time slot #1 that make the Frame that is sent out comprise this Frame with adjustment USTS.
The timing diagram of Fig. 8 situation that to be expression shift to an earlier date according to the compressed mode transmission time started for the synchronization timing that adapts to USTS according to the present invention.The timing diagram of Fig. 9 situation that to be expression postpone according to the compressed mode transmission time started for the synchronization timing that adapts to USTS according to the present invention.
In not using the situation of compact model, the transfer rate of the Frame of each time slot is identical.But under the situation of compact model, the data transmission rate of time slot is faster than the data transmission rate in the normal mode that does not use compact model.The substantial data transmission needs time ratio 10ms to lack.
In compact model,, regularly can under the situation of obliterated data not, carry out synchronously if adjust the timing that time slot interrupts.In other words, for carrying out the USTS pattern, first or last time slot of Frame were adjusted by the time difference, and wherein data do not send.
For adjusting the timing of Frame, mobile radio station and BTS should receive correct timing, and therefore, timing information need be added to RRC message and NBAP message.Regularly transmission not only can be added to first time slot and last time slot, and is added to interrupted another time slot of its transmission in compact model.In the case, should calculate correct timing corresponding to time slot.
When in compact model according to the interrupted time slot adjustment of transmission regularly the time, the length of corresponding time slot can increase or reduce, it should be notified to MS and BTS before the execution compact model.Therefore, adjust after the timing, this frame can send in the USTS pattern.
Figure 10 is the flow chart of the mode switch process of expression from non-USTS pattern to the USTS pattern, has used compact model when switching when carrying out.
With reference to Figure 10, be described in handoff procedure and finish mode switch process afterwards.
The mode switch timing that RNC determines scrambling code and the channel code of USTS and need be used for the USTS operation in step 1001.Determining for the Frame that uses compact model (the transmission interrupt unit comprises the situation of last time slot #15) or for the Frame that uses compact model (the transmission interrupt unit comprises the situation of the first time slot #1) whether after the execution pattern conversion, according to definite result, select the frame number of applied compression pattern and mode switch.
Usually, if the transmission interrupt unit comprises last time slot #15, the frame number of applied compression pattern has little one (1) the value of frame number than the application model conversion, hereinafter, the former is called " compact model frame number " in this specification, and the latter is called " mode switch frame number ".If the transmission interrupt unit comprises the first time slot #1, the compact model frame number has the value identical with the mode switch frame number.
In order to determine aforesaid compact model frame number and mode switch frame number, RNC prepares message is set up compressed mode operation to BTS parameter in step 1002 by sending compact model.BTS notifies RNC compressed mode operation to be ready to by sending compact model preparation message to RNC in step 1003, and RNC entrusts message to notify BTS Frame number with the applied compression pattern to BTS in step 1004 by sending compact model subsequently.
RNC calculates the reference time of BTS and the time difference T_differ of data between the time of advent from MS, and reconfigures by radio link in step 1005 and to prepare message and send the scrambling code of USTS and channel code, time difference T_differ (perhaps chip offset) to BTS.
BTS 20 is transformed into the USTS pattern in step 1006 and 1007 according to the information ready mode that receives from RNC, and reconfigures and be ready to message by sending radio link, notifies the RNC mode switch to be ready to.
RNC 30 reconfigures by the radio link of issuing BTS 20 in step 1008 and entrusts message to BTS 20 sending mode converted frames numbers.After mode switch arrived the USTS pattern, BTS 20 adjusted the transmission time by being shifted to an earlier date by time difference (perhaps chip offset) or postponing transmission.
RNC 30 sends the physical channel that has scrambling code, channel code, time difference T_differ (perhaps chip offset), the mode switch frame number of USTS and be used for the information of compact model in step 1009 by BTS 20 and reconfigures message and give MS 10.
When carrying out compact model, BTS 20 adjusts the chip offset of the Frame that is used for mode switch in step 1010 with this time difference, and sends the controlled Frame of chip offset.
At this moment, in step 1011, the transmission time under transmission intercourse adjustment compact model.If the transmission time in advance, the last time slot of the Frame of the transmission of being interrupted by time difference T_differ is sent this last time slot subsequently by in advance.If propagation time delay, the last time slot of the Frame of the transmission of being interrupted by time difference T_differ is delayed, and sends this last time slot subsequently to MS.
Similarly, at MS, before the Frame with mode switch frame number sends to BTS, adjust Frame by time difference T_differ.In other words, after transmission the arrival time started always of the up link DPCH of MS, carry out at down link DPCH.
Therefore, finished the timing adjustment based on time difference T_differ, MS reconfigures by BTS generation and transmission physical channel in step 1012 and finishes message to RNC, thereby finishes all handoff procedures.
Use mode switch of the present invention, can provide switching in the radio telecommunications system of supporting USTS, the USTS technology can be implemented and use widely like this.
When reference time of the mode switch of selecting to be used for difference computing time, by using compact model, the arrival time started of the Frame that BTS can the select time differential closely sends from MS.In other words, data transmission rate is based on that compact model increases, and data transmission period has reduced, and produces free time.Conversion of BTS execution pattern and regularly adjustment, thus prevented owing to switch the decline of the communication quality that causes.
Though disclose the preferred embodiments of the present invention for illustrative purposes, but those of ordinary skills are to be understood that, under the situation that does not break away from the scope of the present invention that limits by appended claims and spirit, can make various modifications, replenish and replace it.